i use Lynx Version 2.8.5 rel.1 (04 Feb 2004) under DOS 6.22
and try to use the following keys.

KEYMAP is an optional feature, and (I don't recall why) is not supported
under DOS or Cygwin (reading the code to see how it is enabled).

KEYMAP is supported and works fine under DOS (and I believe Cygwin).

ok - I was reading this chunk in LYCurses.h:
#if !defined(__DJGPP__) && !defined(__CYGWIN__)
#define USE_KEYMAPS 1
#endif
(I also recall reading some comments to the effect that the pad support in
PDCurses didn't work well - but that's a while back).

and i get the following error message.
key remapping of { to SHIFT_LEFT failed
key remapping of } to SHIFT_RIGHT failed
key remapping of | to LINEWRAP_TOGGLE failed
what is wrong here? and what must i do to work the keys?

The problem is that the functions SHIFT_LEFT, SHIFT_RIGHT, and
LINEWRAP_TOGGLE aren't supported under DOS or MINGW, but should be
under Cygwin. They are built in only if USE_CURSES_PADS is defined.
This is not defined when PDCurses is used (see LYCurses.h). If you
define USE_CURSES_PADS anyway under PDCurses, the left and right shift
functions work, but the linewrap toggle doesn't, so I am not sure that
it is of much use.
I don't know how to make the functions useful if you really need to
run under DOS 6.22. If you can run under Windows, I would try a Cygwin
binary, which should work. I haven't built a Cygwin binary myself in
some time, but checking an old 2.8.5pre.3 which I built with ncurses
5.3, it behaves as does the current DJGPP version when USE_CURSES_PADS
is defined (i.e. shifting works, but not linewrapping). Does the
linewrapping function really work under some build conditions?

yes/no: when I wrote it, it did something useful; I noticed and have it
as a low-priority bug that IZ's patches changed it to do something which
is only marginally useful (there are a lot of low-priority bugs ;-).